Spray arm for a dishwasher with two spray arm parts

ABSTRACT

In a spray arm for a dishwasher, comprising a first spray arm part and a second spray arm part, of which the first spray arm part comprises a groove which extends substantially along the circumference of the first spray arm part, said groove being formed by a first, inner groove wall and a second, outer groove wall, and of which the second spray arm part comprises a web wall which extends substantially along the circumference of the second spray arm part and engages with the groove, the web wall comprises a first latching element which, in order to establish a latching connection between the first and the second spray arm part, is designed to interact with a second latching element which is located on one of the groove walls.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority on U.S. Provisional Patent Appl. No.61/739,306 filed on Dec. 19, 2012, the entire disclosure of which isincorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The invention relates to a spray arm for a dishwasher, comprising afirst spray arm part and a second spray arm part, of which the firstspray arm part comprises a groove which extends substantially along thecircumference of the first spray arm part.

2. Description of the Related Art

In dishwashers, in particular in those used as domestic appliances,rotating spray arms are provided for supplying and distributing washingwater in an associated washing compartment. The spray arms are usuallyassembled using two spray arm parts which enclose a cavity. The washingwater is introduced into the cavity and is thereafter sprayed into thewashing compartment of the dishwasher by means of nozzles, the nozzlesbeing located on at least one of the spray arm parts.

In order to ensure proper functioning of such a spray arm, its cavityhas to be enclosed tightly sealed by the two spray arm parts.Furthermore, the manufacture and the assembly of the spray arm partsmust be cost-effective, as the cost pressure in the manufacturing andthe assembly of such dishwashers is very high, particularly in the fieldof domestic appliances but also in the field of industrial appliances.

The object underlying the invention is to provide a dishwasher with aspray arm, of which the spray arm parts may be manufactured andassembled in a particularly cost-effective way, but at the same timemeet the requirements in respect of leaktightness over the service life.

SUMMARY OF THE INVENTION

The object is achieved according to the invention with a spray arm for adishwasher, comprising a first spray arm part and a second spray armpart, of which the first spray arm part comprises a groove which extendssubstantially along the circumference of the first spray arm part, saidgroove being formed by a first, inner groove wall and a second, outergroove wall, and of which the second spray arm part comprises a web wallwhich extends substantially along the circumference of the second sprayarm part and engages with the groove, the web wall comprising a firstlatching element which, in order to establish a latching connectionbetween the first and the second spray arm part, is designed to interactwith a second latching element which is located on one of the groovewalls.

The solution according to the invention provides a cavity which can bemanufactured cost-effectively and is sealed toward the outside andconducts fluid. The cavity herein is already sealed without anyadditional measures upon connection of the two spray arm parts to oneanother. No separate production step is required in order to seal thecomponents joined with one another. The sealing is ensured only by thegroove and the web wall inserted into it, with the components at thesame time being permanently coupled to one another by means of thelatching connection provided. The inner groove wall serves as anadditional support for the web wall and in this way increases thestrength of the connection. The structure of the groove provided by theinvention creates double side walls in the spray device. This isadvantageous with a view to torsional stiffness and the stability of theassembled spray arm. The double design of the wall is implemented at thepoints exhibiting the greatest stress, shearing forces and pressureimpulses and at the same time the lowest bending strength.

In particular, the solution according to the invention does notnecessitate any separate process steps for sealing or joining, as in,for instance, paddle welding, vibration welding or overmolding ofconventional spray arm parts. Additionally, the risk of leaks ordistortion as indeed occurs in conventional manufacturing methods forspray arms is avoided. As a result, according to the invention, therequirements in terms of technical equipment for the manufacture andassembly, and the associated investment costs, are reduced. Moreover,the solution according to the invention can be very well integrated intoany automated manufacturing process with short cycle times, inparticular with a view to a short-cycle injection molding process forthe manufacture of the respective spray arm parts.

Based on the solution according to the invention, a spray arm may bemanufactured which also satisfies high esthetic requirements, as existtoday for a spray arm, this being a visible part of a dishwasher.

To this end, in particular the first latching element is embodied on theoutside of the web wall and the second latching element is embodied onthe second, outer groove wall. The latching connection of this kind islocated, hidden from the viewer from the outside, between the outergroove wall and the web wall. Indeed, in this solution no latch cams, asmay be conventionally known from other applications, are identifiable.Because such latch cams should not be visible, such latch cams havehitherto been used only on, for instance, spray arms of the so-calledthird spray level, where the spray arm is located very close to theceiling of the washing compartment. There, not only is the visibility ofthe spray arm is limited, but there is also no requirement for a highlevel of leaktightness.

In the solution according to the invention, it is particularlypreferable that the second, outer groove wall is designed to be higherthan the first, inner groove wall. In this instance, the outer groovewall extends particularly far beyond the web wall, with sufficient spacefor the location of a latching connection thus being available below. Atthe same time, the groove walls of different height permit the web wallto be inserted into the groove in a stepped manner, said web wall beingfirst aligned along the outer groove wall and only then being insertedinto the rear or deeper section of the groove for the purpose of sealingby means of the inner groove wall. This stepped insertion into thegroove is particularly advantageous with a view to an automated assemblyand the leaktightness of the functional group thus achievable.

In order to further facilitate the assembly of the functional groupaccording to the invention, the first, inner groove wall is preferablyalso designed with an insertion chamfer on its rim facing the web wallfor insertion of the web wall into the groove, the second, outer groovewall is preferably also designed with an insertion chamfer on its rimfacing the web wall for insertion of the web wall into the groove,and/or the web wall is preferably also designed with an insertionchamfer on at least one of its rims facing the groove walls forinsertion of the web wall into the groove.

For the latching connection according to the invention, the firstlatching element is preferably designed as a detent lug and the secondlatching element as a detent recess. With a latching geometry of thiskind, a high strength of the latching connection may be achieved with acomparatively narrow latching width.

The first latching element and the second latching element arefurthermore preferably designed to extend substantially along the entirecircumference of the first and the second spray arm part. By means ofthe thus substantially completely surrounding latching connection, thetwo spray arm parts are coupled together in a uniformly tight manneralong their entire circumference. The risk of any local detachment,loosening or bursting open of the connection is thus minimized, given atthe same time a comparatively low locking force. The surroundinglatching may herein be advantageously combined on at least one of thespray arm parts with a surrounding sealing lip, which in the latchingprocess with its counterpart is compressed and deformed along the entirecircumference. Such a sealing lip is, however, not mandatory. Rather,the surrounding latching according to the invention especiallyadditionally forms a labyrinth which significantly contributes to themutual sealing of the two spray arm parts. The solution according to theinvention thus achieves an optimum balance between joining force anddeformation and leaktightness. The particular embodiment of the latchinggeometry according to the invention additionally contributes towardleaktightness being ensured along the entire circumference of the twospray arm parts.

Moreover, it is advantageous that the first latching element and thesecond latching element are designed with an interruption by a short gapat predetermined spacings along the circumference of the first and thesecond spray arm part. Such interruptions of the latching elementsadvantageously extend over a gap of 0.5 cm to 1.5 cm, particularlypreferably approx. 1.0 cm, and are of advantage in particular with aview to the shaping of the injection molds used for the spray arm parts.

Finally, the solution according to the invention is also outstandinglysuited to providing at least one channel leading from the outside intothe groove for accommodating a mass connecting the first spray arm partwith the second spray arm part. The mass introduced into the channel mayensure an additional means of sealing and a cohesive connection of thetwo spray arm parts, if so desired.

In the following, exemplary embodiments of the solution according to theinvention are explained in more detail with reference to the attachedschematic drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a first perspective view of a first spray arm according tothe invention with its two spray arm parts prior to assembly.

FIG. 2 shows a second perspective view of the spray arm parts shown inFIG. 1.

FIG. 3 shows a perspective view of the spray arm parts shown in FIG. 1after assembly to form the complete spray arm.

FIG. 4 shows the cross section IV-IV in FIG. 1.

FIG. 5 shows the cross section V-V in FIG. 3.

FIG. 6 shows the detail VI in FIG. 5.

FIG. 7 shows the view shown in FIG. 5 for a variant of a spray armaccording to the invention.

FIG. 8 shows a perspective view of a second spray arm according to theinvention with its two spray arm parts prior to assembly.

FIG. 9 shows a perspective view of the spray arm parts shown in FIG. 8after assembly to form the complete spray arm.

FIG. 10 shows a perspective view of a third spray arm according to theinvention with its two spray arms prior to assembly.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The figures show a spray arm 10 of a domestic dishwasher which is notillustrated, comprising a vertical hollow-cylindrical hub section 12,with two arm sections 14 and 16 extending horizontally therefrom inopposite directions. When fitted to the dishwasher, the spray arm 10 issupplied through the hub section 12 with water under pressure, whichwater then sprays out through the nozzles 18 which are arrangeddistributed on the spray arm 10.

The nozzles 18 are distributed on the upper side 19 of an upper,shell-shaped spray arm part 20 and, if appropriate, also on the lowerside 22 of a lower, also shell-shaped spray arm part 24. The spray armparts 20 and 24 herein are made of plastic by means of injection moldingor alternatively of metal, in particular of stainless steel, by means ofdeep-drawing, and are each placed against one another by way of theirshell shape such that a cavity 26 is created.

The region of the joint or connection between the two shells placedagainst one another in such a way is sealed and coupled in aform-fitting manner. To this end, a groove 28 which extendssubstantially along its circumference is embodied on the upper spray armpart 20, said groove being formed by a first, inner groove wall 30 and asecond, outer groove wall 32. Furthermore, a web wall 34 which alsoextends substantially along its entire circumference and engages withthe groove 28 is embodied on the lower spray arm part 24.

The web wall 34 is, at its top, designed to be so high that it is sealedagainst the upper spray arm part 20 right up to the base of the groove28 and there in a first, upper seal region 36 (refer to FIG. 6) bypressing in a force-fitting manner. Furthermore, the groove 28 isdesigned to be so narrow that the web wall 34, when inserted into thegroove 28, is laterally forced against the inner groove wall 30, whereit is also sealed in a second lateral seal region 38 (refer again toFIG. 6) against the upper spray arm part 20. Alternatively, the web wall34 is designed to be so high and/or wide that it lies against the wallsof the groove 28 without any major contact pressure. In this instance,sealing between the upper spray arm part 20 and the lower spray arm part24 is essentially achieved solely as a result of the labyrinth-typegeometry of groove 28 and web wall 34.

A latching connection 40 is further achieved between the upper spray armpart 20 and the lower spray arm part 24, by means of which connectionthe two parts are coupled to one another in a form-fitting manner. Theform-fitting coupling is made without a separate production step whenjoining the spray arm part 20 and the spray arm part 24 during assemblyof the spray arm 10. For this purpose, the web wall 34 on the lowerspray arm part 24 comprises a first latching element 41 on its outsidewhich interacts with a second latching element on the inside of theouter groove wall 32. The latching connection 40 of this kind is notvisible to anyone viewing the spray arm 10 from the outside.

The first latching element 41 is designed as a detent lug and the secondlatching element 42 as a detent recess, both extending substantiallyalong the entire circumference of the first and the second spray armpart 20 or 24, respectively, and only being interrupted by a short gap44 at predetermined spacings along the circumference.

The second, outer groove wall 32 is designed to be higher than thefirst, inner groove wall 30 and extends far beyond the web wall 34 whenthe lower spray arm part 24 is brought together with the upper spray armpart 20. Moreover, the first, inner groove wall 30 is designed with aninsertion chamfer 46 on its rim facing the web wall 34 for insertion ofthe web wall 34 into the groove 28, the second, outer groove wall 32 isdesigned with an insertion chamfer 48 on its rim facing the web wall 34also for insertion of the web wall 34 into the groove 28, and the webwall 34 itself is designed with an insertion chamfer 50 and 52 on eachof its two rims facing the groove walls 30 and 32. By means of theseinsertion chamfers 46, 48, 50 and 52, the insertion of the web wall 34into the groove 28 overall is also possible in the event of relativelylarge dimensional differences between spray arm part 20 and spray armpart 24.

FIG. 7, finally, shows a variant of a spray arm 10 in which a pluralityof channels 54 for accommodating a mass connecting the first spray armpart 20 with the second spray arm part 24 are distributed along thecircumference on the upper rim region of the upper spray arm part 20.The mass may be introduced into the channels 54 during the assemblyprocess, in particular in order to be distributed within the groove 28above the web wall 34, for additional sealing and for cohesiveconnection of the two spray arm parts 20 and 24.

FIGS. 8 and 9 show a spray arm 10, of which the spray arm part 20 isalso designed with a groove 28, an inner groove wall 30 and an outergroove wall 32. A substantially vertical slot 56 is formed in the outergroove wall 32 approximately in the center of each arm section 14 and16. The slot 56 extends substantially along the entire height of thegroove wall 32 and is open toward the outside and/or accessible fromoutside. A fin 58 is inserted in the slot 56 of this kind in aform-fitting manner when the two spray arm parts 20 and 24 are joined,said fin 58 being embodied at a corresponding position on the exteriorof the web wall 34 of the lower spray arm part 24. The fins 58 of thiskind, of which a total of four are located on the circumference of thespray arm part 24, in interaction with the four associated slots 56 onthe upper spray arm part 20, serve as stiffening elements and inparticular prevent any distortion of the spray arm 10 when water passesthrough it in the operational state and thus sets it in rotationalmotion.

FIG. 10 shows a spray arm 10 in which, in a functionally similar manner,vertical slots 56 are embodied on the inner groove wall 30 and fins 58are embodied on the inner side of the web wall 34. This arrangement ofthe slots 56 and the form-fitting ribs 58 results in a stiffening effectwhich is not visible from outside.

In concluding, it should be observed that all features mentioned in theapplication documents and, in particular, in the dependent claims are tobe protected in their own right individually or in any combination withone another, notwithstanding the formal references made to one or morespecific claims.

What is claimed is:
 1. Spray arm (10) for a dishwasher, comprising afirst spray arm part (20) and a second spray arm part (24), of which thefirst spray arm part (20) comprises a groove (28) which extendssubstantially along the circumference of the first spray arm part (20),said groove being formed by a first, inner groove wall (30) and asecond, outer groove wall (32), and of which the second spray arm part(24) comprises a web wall (34) which extends substantially along thecircumference of the second spray arm part (24) and engages with thegroove (28), the web wall (34) comprising a first latching element (41)which, in order to establish a latching connection (40) between thefirst and the second spray arm part (20; 24), is designed to interactwith a second latching element (42) which is located on one of thegroove walls (30; 32).
 2. Spray arm of claim 1, wherein the firstlatching element (41) is embodied on the outside of the web wall (34)and the second latching element (42) is embodied on the second, outergroove wall (32).
 3. Spray arm of claim 2, wherein the second, outergroove wall (32) is designed to be higher than the first, inner groovewall (30).
 4. Spray arm of claim 3, wherein the first, inner groove wall(30) is designed with an insertion chamfer (46) on its rim facing theweb wall (34) for insertion of the web wall (34) into the groove (28).5. Spray arm of claim 4, wherein the second, outer groove wall (32) isdesigned with an insertion chamfer (48) on its rim facing the web wall(34) for insertion of the web wall (34) into the groove (28).
 6. Sprayarm of claim 5, wherein the web wall (34) is designed with an insertionchamfer (50, 52) on at least one of its rims facing the groove walls(30; 32) for insertion of the web wall (34) into the groove (28). 7.Spray arm of claim 6, wherein the first latching element (41) isdesigned as a detent lug and the second latching element (42) as adetent recess.
 8. Spray arm of claim 7, wherein the first latchingelement (41) and the second latching element (42) are designed to extendsubstantially along the entire circumference of the first and the secondspray arm part (20; 24).
 9. Spray arm of claim 8, wherein the firstlatching element (41) and the second latching element (42) are designedwith an interruption by a short gap (44) at predetermined spacings alongthe circumference of the first and the second spray arm part (20: 24).10. Spray arm according of claim 9, wherein at least one channel (54)leads from the outside into the groove (28) for accommodating a massconnecting the first spray arm part (20) with the second spray arm part(24).
 11. Spray arm of claim 1, wherein the second, outer groove wall(32) is designed to be higher than the first, inner groove wall (30).12. Spray arm of claim 1, wherein the first, inner groove wall (30) isdesigned with an insertion chamfer (46) on its rim facing the web wall(34) for insertion of the web wall (34) into the groove (28).
 13. Sprayarm of claim 1, wherein the second, outer groove wall (32) is designedwith an insertion chamfer (48) on its rim facing the web wall (34) forinsertion of the web wall (34) into the groove (28).
 14. Spray arm ofclaim 1, wherein the web wall (34) is designed with an insertion chamfer(50, 52) on at least one of its rims facing the groove walls (30; 32)for insertion of the web wall (34) into the groove (28).
 15. Spray armof claim 1, wherein the first latching element (41) is designed as adetent lug and the second latching element (42) as a detent recess. 16.Spray arm of claim 1, wherein the first latching element (41) and thesecond latching element (42) are designed to extend substantially alongthe entire circumference of the first and the second spray arm part (20;24).
 17. Spray arm of claim 16, wherein the first latching element (41)and the second latching element (42) are designed with an interruptionby a short gap (44) at predetermined spacings along the circumference ofthe first and the second spray arm part (20: 24).
 18. Spray armaccording of claim 1, wherein at least one channel (54) leads from theoutside into the groove (28) for accommodating a mass connecting thefirst spray arm part (20) with the second spray arm part (24).